Screen



Dec. ll, 1928. 1,694,706

A. HERZ SCREEN Original Filed Jan. 22, 1917 MWMM Patented Dec. '11, 192s.

UNITED STATES PATENT OFFICE.

ALFRED HERZ, 0F CHICAGO, ILLINOIS.

SCREEN.

Original application led January 22, 1917, Serial N0. 143.613. Divided and this application led December 1G, 1926.

My invention relates to a screen for making visible light images projected thereon.

.Screens for this purpose a re known but do not provide the novel means for excluding the disturbing effect of extraneous light which is the essence et the present invention.

The prevent application is divisional in part of my copendinpY application, Serial No. 143,618, filed January 2Q, 1917, now Patent No. 1,614,672, January 18, 1927. f

The invention may be applied to different specific uses such, for example, as forming the ground or iield plete oi a camera finder or a. ,picture projecting screen and the like.

TheA principle upon Whichiny invention proceeds is the following. A. plate er sheet is provided with light diffusing means such as a ground or matted surface on thesurface of a transparent or semi-transparent medium1 The sheet may be a thin iight diffusing body or contain light diil'using material on its sur tace or Within its body. This light diffusing means makes the iight image visible in e. definite position or plane and it may be termed an image holding Between the eye of the observer and the said light diiiusing oriinage holding ineens a layer or body oi light .absorbing means is interposed. This layer or body may be e part ci the means for supporting the light diffusing or image holding means such as the glass or other transparent plate or sheet, i. e., a layer on or in the same or may be formed by introducing linto the glass oro'ther transparent plate a stain, dye or other light ab-M sorbing medium Which tends to hinder 0r oppose the passage of light.

Instead of the absorbing means such as stained glass or thev like supporting the light diffusing means, namely, the frosted surface, the light diffusing means may be a sheet or plate self-supporting such, for instance, as'

thin semi-transparent fibrous material such as oiled or waxed paper sized cloth or the like and the light absorbing means may constitute a. layer or prepared surface supported thereby. j

The image projecting means which may be the finder lens of the view finder or may be the picture projecting means is placed back of the image holding sheet, plate or surface with the light absorbing sheet, plate or surface between the eye of the observer and the image holding means. The light from the Serial No. 155,135.

image which is held or formed on the image holding means passes through the light absorbing medium 1 and then strikes the eye ot' the observer. Extraneous light which may come from the observers side of the screen Will pass through the light absorbing medium before it strikes the image holding surface and again pass through the light 'absorbing medium before striking the eye of 'the observer.

The light absorbing medium need notbe absolutely uniform' throughout, it may be broken up into lines, points or the like, but for best eiieet it should give to the eye ot the observer a generally uniform held or effect.

In order to acquaint thosesliiiled in the art With the manner of constructing and operating a device embodying my invention l shall describe in connection with the accompanying drawings a specific embodiment of the saineu Figure 1 is a diagram of a screen of my invention embodied in. a. view inder such is employed in cameras or the like;

llig. 2 is a similar diagram indicating the manner of using the screen of my invention in connection with the projection of pictures.

ln big. 1 the parts otheiinder are indicated only as 'to essentials.

Theobject 17d in front oi the lens 171 throws od rays of light which are directed by the lens 171 upon a suitable mirror 172 inclined at a suitable angie to throw 'the rays of light. upon the iieid plate or image receiving plate 173 which heretofore has consisted of ground clear glass. That is tosay, this plate. has heretofore lbeen entirely con structed of transparent plate of glass hav ing one side orsurface frosted or matted 'for the purpose of receiving the image formed bythe lens 171. l have found that in em- ,n

ploying such a. field plete it is subject te interference from external light to such an extent that a shield is almost indispensible. Assume that a ray ot light 1,74; coming from a sourcey 175 falls upon the piste 173, itis broken up at 'the frosted or matted suraee of the field plate and the light therefrom is directed into the eye of the observer at 176, this amount of light beingparticularly, When the shy overhead is bright or there are other conflicting lights, of such quantity as to in terere very seriously with the image 177 which appears upon the field plate. In order to correct for external and extraneous light,

I have changed the character of the field plate tion but once. Experiments with this type ot iield plate of image receiving plate shows that the same is very little affected regardless of the type ot overhead light.

I have employed for this purpose thin plates of gelatin, Celluloid, glass, and the like` stained with a suitable dye or color, the lower surface being ground, frosted or matted as indicated at 178, to form the actual image receiving surface, and the plate or film above forming a supporting means for the surface, and forming the obstruct-ing means for obstructing external light such as that illustrated b v theray 17% in Figure 1. rl`he dye or color which forms the light obstructing means may be evenly distributed throughout the body of the plate or may be contained in a layer. IIhe image forming surface may be formed 'otherwise than by matting, grinding or frosting the surface, as :tor instance, by adding a thin layer of material suitable for making the image apparent. I consider this orm of field plate or image receiving plate to be broadly new.

Where the means which forms the image holding medium is a self-supporting sheet, plate or the like, the dye or other light absorbing means may be placed in a layer either uniformly or in lines, dots or other regular patterns to give a regular edect upon the surface adjacent the eye of the observer. T he color which I have successfully used in the practice of this invention is a cobalt blue for the glass plate 173 either in the glass or placed upon the surface of the same.

In Fig. 2 I have shown the screen 17 3 as applied to the viewing of pictures projected bythe picture projecting device 180. A light excluding box 181 may be placed between the held or' screen 17 3 and the lens of the picture projecting machine to exclude extraneous light from that side of the screen, certainly this would be unnecessary on a darkened stage.

The operation of this form of the device is the same as above described.

I do not intend to be limited to the precise details of construction shown and described.

I claim:

A1. In a screen of the class described', a' plate of transparent material having embodied therein a light obstructing substance, one surface of said plate being ground or matted. v 2. A screen of the ,class described comprising a sheet of material having one surface thereof ground or matted to receive and make apparent an image, said screen comprising a light hindering substance, said sheet being of suiicient transparency to permity the light from the image to be viewed through the sheet.

3. In a device lof the class described, a unitary integral sheet embodying a light diffusing medium lyingjin substantially a single plane to hold an image in said plane and a light obstructing medium parallelmg said image holding medium and lying between the latter and the eye of the observer.

4. In a screen of the class described. a transparent glass sheet having a light obstructing material embodied therein and having one surface thereof which is adapted to tace the projection device, roughened to provide a tine granular screen for receiving and malring apparent an image.

In witness whereof, I hereunto subscribe my name this 14th day o December, 1926.

` ALFRED HERZ. 

